How navies reused captured cannon

Were captured cannon routinely recast for naval service during the age of sail?

Usually not. Working guns were reused, sold, or placed in the general pool, with remounting far more common than recasting.

The practical distinction is between changing the weapon and adapting its carriage. Iron cannon were rarely worth recasting when they already worked. Expensive bronze pieces might be treated differently, and unsuitable land guns could justify more intervention. A navy could also sell an unwanted weapon or place it in the general ordnance pool. Remounting was the common step because it adapted captured ordnance to a ship without discarding a usable barrel.